Data collected from 3,000 sites in 15 countries has shown that populations of at least 17 European butterfly species have declined by an average of 70 percent in the last 20 years. This worrying figure points to a much wider loss of biodiversity in the meadows of Europe, with grassland butterfly populations used as indicators for the overall health of grassland ecosystems.

The Lulworth skipper (Thymelicus acteon), a small butterfly in decline.

Sustainably managed semi-natural grasslands support high levels of biodiversity, including plants, butterflies and many other insect groups; however, the abandonment of traditional livestock-grazing and hay-making practices in favour of more intensive, and more profitable, farming methods have led to many species disappearing from these areas altogether.

The sharp declines in butterfly populations are largely due to the rapid economic and social changes that have taken place in Europe over the last few decades. Traditional farming methods in particular have changed drastically, with land that had been farmed for generations being abandoned where it is unable to support modern agricultural practices, or turned over to intensive farming, resulting in widespread deterioration of the once diverse grasslands. Many young people are also turning away from farming and moving to the cities, leaving behind the rural communities and the traditional methods of managing the meadows.

The small copper (Lycaena phlaeus), one of the species used for the Grassland Butterfly Indicator.

A change in the EU agricultural policy is necessary if butterflies are to once again flourish on European meadows. Dr Martin Warren, Chief Executive at Butterfly Conservation (UK) is advocating a change to farming in areas of High Nature Value (HNV), which are vital for the survival of grassland butterflies across Europe, such as the alpine meadows, pasture and steppe in eastern and southern Europe, Spain and Portugal.

The redirection of Common Agricultural Policy (CAP) funding to support sustainable farming of HNV areas is considered by butterfly conservationists as vital to halting further losses and supporting the recovery of grassland butterflies in Europe. Under a HNV approach, farmers would be encouraged to return to the traditional methods of grassland management, in return for better support and incentives under new European policy, which could be decided in the next round of CAP reform in 2013. Butterfly Conservation Europe is also pressing for grassland butterflies to be adopted as agricultural indicators, incorporating them into EU policies for monitoring the health of important ecosystems.